Analysis of the Effect of Delay Spike and Initial Congestion Window Size on TCP Performance in Wireless Cellular Networks

摘要

Previous research indicates that increasing the initial TCP congestion window from one segment to roughly 4 KB can significantly improve the performance of the TCP for file transfers that are smaller compared to the link bandwidth-delay product in wireless cellular networks. However, these networks are likely to experience delay spikes exceeding the typical round-trip-time figures, which can cause spurious timeouts that lead to unnecessary retransmissions and reduction of the TCP sender's transmission rate. Consequently, more unnecessary retransmissions are needed for the large initial window and thus the throughput of the TCP is degraded. This paper presents some research results on using large initial windows over wireless cellular network. It has been shown that the throughput of TCP connection over a single bottleneck link with FIFO transmission is degraded with enlarging initial window in the presence of delay spikes. Furthermore, TCP throughput performance is kept unchanged when there is no burst delay. All these findings should be considered while setting up initial congestion window.